NAME
vcons —
generic virtual console
framework
SYNOPSIS
#include
<wscons/wsdisplay_vconsvar.h>
int
vcons_init(struct
vcons_data *vd, void
*cookie, struct
wsscreen_descr *desc,
struct wsdisplay_accessops
*accops);
int
vcons_init_screen(struct
vcons_data *vd, struct
vcons_screen *scr, int
exists, long
*defattr);
void
vcons_redraw_screen(struct
vcons_screen *scr);
DESCRIPTION
These functions are used to setup and control the generic virtual console framework.The
vcons_init()
function initializes the framework, it needs to be called for each driver
that's going to use vcons.
vcons_init_screen()
adds a virtual screen to a display.
vcons_redraw_screen()
redraws a screen. A driver should call it when returning to terminal
emulation mode, for instance when X exits.
struct vcons_data contains all information needed to manage virtual consoles on a display, usually it will be a member of the driver's softc.
struct vcons_screen describes a virtual screen.
USAGE
To use vcons with a driver it needs to be initialized by calling
vcons_init(),
usually in the driver's attach function.
- vd
- should be a pointer to the driver's struct vcons_data.
- cookie
- should be a pointer to the driver's softc.
- desc
- should point to a struct wsscreen_descr describing the default screen type for this display.
- accops
- points to the driver's struct wsdisplay_accessops so
vcons_init() can fill it in with its own implementations ofalloc_screen(),free_screen(), andshow_screen().
A driver should however provide its own
ioctl() and
mmap()
implementations. Both will receive a pointer to the driver's
struct vcons_data as first parameter.
After initialization the driver needs to
provide a callback function that will be called whenever a screen is added.
Its purpose is to set up the struct rasops_info
describing the screen. After that the drawing methods in
struct rasops_info will be replaced with wrappers
which call the original drawing functions (which may or may not be provided
by the driver) only when the respective screen is visible. To add a virtual
screen the driver one should call
vcons_init_screen()
which will call the callback function described above, allocate storage for
characters and attributes based on whatever the callback set up in
struct rasops_info, and add the screen to a list kept
in struct vcons_data.
The callback needs to have this form:
void
init_screen(void
*cookie, struct vcons_screen *scr,
int existing, long *defattr)
and should be stored in the init_screen member found in struct vcons_data. The arguments are:
- cookie
- is the cookie passed to
vcons_init() - scr
- points to the struct vcons_screen being added, its scr_ri member, a struct rasops_info, needs to be filled in.
- existing
- is non-zero if the screen already exists and is only added to the list.
- defattr
- points to the screen's default text attribute. It's filled in by
vcons_init_screen() by calling thealloc_attr() method found in struct rasops_info.
When attaching a
wsdisplay(9) the accesscookie member of the
struct wsemuldisplaydev_attach_args passed to
config_found()
needs to be a pointer to the driver's struct
vcons_data.
The following members of struct vcons_screen may be of interest to drivers:
- scr_ri
- contains the struct rasops_info describing the screen's geometry, access methods and so on.
- the value passed as cookie to
vcons_init(). Usually the driver's softc. - scr_vd
- the driver's struct vcons_data.
- scr_flags
- can be zero or any combination of:
VCONS_NO_REDRAW- don't call
vcons_redraw_screen() when this screen becomes visible. VCONS_SCREEN_IS_STATIC- don't free(9) this screen's struct
vcons_screen in
free_screen() - useful if the screen has been statically allocated.
- scr_status
- currently contains only one flag,
VCONS_IS_VISIBLE, which is set when the screen is visible.